Stabilized aviation gasoline



hPa'tcnted Apr. 10, 19 45 STABILIZED AVIATION GASOLIN John E. Mltal,Alton, EL, asslgnor to Shell Development Company san Francisco, Calif.,a

corporation of Delaware No Drawing. Application'April 27, rats,

' Serial No. assass- (ores-s9) This invention relates to inhibitors foraviation gasoline containing tetra-alkyl lead, which inhibitors increasethe storage stability of said gasolines.

It is an object of the invention to produce motor fuel compositions ofenhanced storage stability, particularly aviation fuels. Another purposeis to provide new and improved inhibitors for leaded aviation gasoline.Other objects will be apparent from the following description' I havefound that the addition of hydrobromic or hydriodic acid to an oxidationinhibitor comprising an amino phenol greatly increases the stability ofan initially stable gasoline containing tetra-alkyl lead and theinhibitor. Gasolines which are susceptible to this treatment forretarding their decomposition are relatively stable compositions such asstraight run or casing head gasoline, allwlated fractions such asiso-octane, and the. like. Although such hydrocarbons have acomparatively long life when stored alone, their age decomposition istremendously accelerated whenthe conventional quantity (up to about 8ccJsal.) of tetra-alkyl lead is added to the fuel to increase its mockrating. In such a gasoline, both the initially stable hydrocarbons andthe upon standing so that the natural life of the gasoline is greatlyshortened byth'e occurrence of both lead precipitate and organic gumformation.

$19 I Inhibit .tetra-alkyl lead disintegrate at a fairly rapid rate Onthe other hand,;for some undetermined reason, hydrobromic' or hydriodicacid does not exhibit this enhancing efiect in' the presence of aminophenolic inhibitors when the inhibitors are used to stabilize a cracked(i e. unsaturated) or originally unstable gasoline. My inhibitors thusexhibit their principal stabilizing power in preventing thedecomposition of tetra-alkyl lead which is dissolved in gasoline orother motor fuel.

' The hydrobromic or hydriodic acid may advantageously' be present inany amount up to the stoichiometric quantity necessary to neutralize thebasic amino phenolic inhibitor. Less than this equivalent amount willhave an eflect proportionate to the quantity present, while any amountin excess of the stoichioinetrical quantity will have no additionalinhibiting eflect and on the contrary'may possess the disadvantage ofbeing corrosive. I

This enhancing eflect maybeiilustrated by the the following examples inwhich straight run gas- Inhibitor A bad the following composition:

- The amount of hydrogen bromide used in inhibitor A in trials 2 and 4was only the amount necessary to neutralize the inhibitor.

Induction Inhibitor A ibitor -I InhibitorBhydrobz-omlde The improvementin induction periods obtained in these tests on the basis of equalweights oiv inhibitors was even greater than the simple nu-- mericaldiflerence between the figures in the last column above, since theamount of amino phenol itself in the quantity of amino phenolhydrobromide used is obviously considerably less than the equal weightor unneutralized amino phenol taken for comparison.

This enhancing eifect is observed only when amino phenols are employedwith hydrobromic acid or hydriodic acid. Inhibitors containing only theamino group or only the phenolic group do not exhibit such increasedanti-oxidant ability. Indeed, hydrobromic acid exhibits anadverse-effect' in the presence of non-amino phenolic inhibitors.

The amino group of the phenolic inhibitor be a primary amine, or onehydrogen may be substituted (to produce a secondary amine) by suchgroups asmethyl, ethyl, nand iso-propyl,

normal tertiaryand iso-butyl, amyl, hexyl,

cyclohexyl, acetyl, acetonitrile, butylidene, heptylidene, benzylidene(as well as'chloror nltrobenzylldene), cinnamylidene, furfuryl, and thelike, their analogues, homologues and suitable substituted derivatives.

oline containing 4'cc. tetra-ethyl lead per gallon or diflerentinhibitors or their hydrobromidcs.

The amino phenolic inhibitor maybe mononucleaisuch as the above or theymay be polynuclear, as well as monoor poly hydroxy, as in aminonaphthol, phenyl or benzyl .mino mph- Inhibitor B consisted of benzylp-amino phenol.

thol, amino anthranol, amino phenanthrol, ami- A -no 61- or tri-hydroxynaphthalene, etc.

When more than one =NH cr -NH: group is found in the phenolic compound,sufl'ioient hydrobromic or nydriodic acid may be employed tounstable onstorage and a stabilizing simulate! a compound selected'irom the. groupor primary and secondary ar'nino phenol hydroneutralize all primary orsecondary amines presout.

In general, concentrations of my amino phe-." nolhydrobromide or aminophenolhydriodic inhibitors between about 0.0005% and 0.1% and morepreferably between about 0.0005% and .004% are adequate to stabilize atypical aviation or saturate type gasoline.

The hydrobromic or hydriodic acid and the amino phenol may be added tothe asoline sepa rately, together, or they may be first mixed in thedesired proportion and incorporated: in the gasoline as needed.

I claim as'my invention:

1. A stable motor fuel comprising a predomi-.

nant amount of a normally stable gasoline type motor fuel containing anamount of tetra=a1kyl leadsumcient to render the mixture relativelyiodides andhydrobromides.

2. The composition of claiml, wherein the tetv. ra-alkyl lead istetra-ethyl lead.

-3.'-The composition oi claim 1, wherein there is substantially nounneutralized amino phenol. 4. The composition of claim '1, wherein thestabilizer is derived from a secondary amino phe 5. The composition ofclaim 1, whereinthe stabilizer is-present in about 0.0005% w. to about.

Q 8. The composition of claim 1, wherein the amino phenol is benzyl paraamino phenol.

- JOHN E.

wherein the amino phenol is N butyl para amino phenol.

